> Carbon nanotubes are not even close to strong enough to build a space elevator, that's the whole problem.
Do you have any sources for that? Because from a quick search online I’m seeing that SE requires a tensile strength of 60-80 GPa and the theoretical max strength of carbon nanotubes can reach 150-200 GPa (with a 63 GPa being demonstrated back in 2000)
Nobody can make a nanotube with a length of one meter, much less with a length of 1 km or of 100 km.
We can imagine a molecular machine that would grow carbon nanotubes like a silkworm grows silk filaments, but we are many decades away from this kind of things.
Moreover, the tensile strength is not all. It must resist to some intentional or accidental collisions, to earthquake waves and so on.
That paper only presents hope that perhaps adhesive bonding of carbon nanotubes could produce a cable with high tensile strength.
It does not contain any experimental results supporting this hope, because only a strength similar to steel has been obtained.
Perhaps it will become possible to obtain a higher tensile strength than with other materials by this method, but it is likely that this will require longer nanotubes and perhaps some other kind of polymeric resin instead of epoxy. It is very difficult to find anything that has high enough adhesion to carbon.
Sure, the material had not been produced yet, and still hasn't. Getting all those long nanotubes to line up parallel is another of the hard parts. It's just a theoretical result.
A key part of the design is for the glue to have a low enough melting point, so if the cable breaks, it melts on reentry and you don't get lots of little fluttery bits instead of a big super-strong cable wrapping around the planet.
Do you have any sources for that? Because from a quick search online I’m seeing that SE requires a tensile strength of 60-80 GPa and the theoretical max strength of carbon nanotubes can reach 150-200 GPa (with a 63 GPa being demonstrated back in 2000)